Dangers to the Global Environment

What are CFCs?

• CFCs are chlorine- and bromine-containing compounds which have been implicated in the accelerated depletion of ozone in the Earth's stratosphere.
• They were invented in the 1930s for use in many household and industrial uses including coolants for refrigeration units, and aerosol propellants.
• In 1973 CFCs were found to be catalytic in ozone depletion.
• In 1985 the polar ozone depletion was announced.
• Effective stratospheric chlorine levels as shown here for midlatitudes will return to 1980 values around 2050. The return to 1980 values will occur around 2065 in polar regions. In 1980, ozone was not significantly depleted by the chlorine and bromine then present in the stratosphere.

How do CFCs hurt the environment?

• CFCs released into the atmosphere accumulate in the stratosphere.
• Stratospheric ozone shields living organisms on Earth from the harmful effects of the Sun's ultraviolet radiation; even a relatively small decrease in the stratospheric ozone concentration can result in an increased incidence of skin cancer in humans and in genetic damage in many organisms.
• CFC molecules break down by the action of solar ultraviolet radiation and release their constituent chlorine atoms.
• These then react with the ozone molecules, resulting in their removal.
• CFCs have a lifespan of 20 - 100 years and so can cause damage long after their release.